To maintain the high efficiency of air source heat pump (ASHP) under frosting conditions, the periodic defrosting is required. The earlier and later defrosting can both cause a decline in its average coefficient of performance (COP) throughout the frosting-defrosting process. Accurately predicting the frosting rate and using it for defrosting control is a fundamental method to solve this problem. However, there is still lack of a universal model for predicting the frosting rate. To solve this problem, a mathematical model for variable-frequency ASHP was developed firstly, which can simulate its operating parameters under different conditions. Combining with the enthalpy diagram, a calculation method for the initial frosting rate of ASHPs was proposed. Then, an initial frosting rate prediction model suit for all operating conditions was developed utilizing the calculation results. Results indicate that the developed frosting rate prediction model for ASHPs demonstrates well predictive performance. The deviations between the predicted values and actual values are mainly within +/- 15 %. Besides, the initial frosting rate can characterize the overall frosting degree and be used to predict the total frost mass throughout the frosting process. The maximum relative error between the predicted total frosting mass and the experimental results is 9.25 %. The findings of this study facilitate the determination of the optimal defrosting time, and develop a new defrosting control strategy for ASHPs to optimize the defrosting performance.
To maintain the high efficiency of air source heat pump (ASHP) under frosting conditions, the periodic defrosting is required. The earlier and later defrosting can both cause a decrease in its average coefficient of performance (COP) throughout the frosting-defrosting process. Accurately predicting the frosting rate and using it for defrosting control is a fundamental method to solve this problem. However, there is still lack of a universal model for predicting the frosting rate. To solve this problem, a mathematical model for variable-frequency ASHP was developed firstly, which can simulate its operating parameters under different conditions. Combining with the enthalpy diagram, a calculation method for the initial frosting rate of ASHPs was proposed. Then, an initial frosting rate prediction model suit for all operating conditions was developed utilizing the calculation results. Results indicate that the developed frosting rate prediction model for ASHPs demonstrates well predictive performance. The deviations between the predicted values and actual values are mainly within ±15
Purpose Construction stakeholders often prioritise the environmental and economic aspects of sustainability over its social dimensions. There is a limited understanding of how the Sustainable Development Goals (SDGs) and occupational health and safety (OHS) intersect and mutually contribute to each other. This study aims to explore the connection between SDGs and OHS in construction. Design/methodology/approach Using a systematised review approach, 46 publications related to the SDGs and OHS from 2015 to 2023 were identified. The data was analysed through thematic analysis, with the SDGs as the main themes. Additionally, examples from Australian Work Health and Safety laws have been used as a case study to illustrate the connection between the SDGs and OHS. Findings Upon in-depth analysis, it was discovered that construction OHS closely relates to ten SDGs: no poverty (SDG 1), good health and well-being (SDG 3), quality education (SDG 4), gender equality (SDG 5), decent work and economic growth (SDG 8), industry, innovation and infrastructure (SDG 9), reduced inequalities (SDG 10), sustainable consumption and production (SDG 12), climate action (SDG 13) and peace, justice and strong institutions (SDG 16). Furthermore, the study revealed that the relationship between the SDGs and OHS is mutual, with each contributing to the attainment of the other. Originality/value The study offers comprehensive insights into the relationship between the SDGs and OHS in the construction industry, thereby contributing to the 2030 Agenda for Sustainable Development.
This study investigated incorporating Ce-NaY zeolite into poly(ether sulfone) (PES) membranes to enhance wastewater treatment performance and reduce environmental impact. PES membranes, while strong and chemically stable, suffer from fouling and limited permeability. Modified membranes showed improved thermal stability (degradation at 350 degrees C) and a porous structure, especially at lower zeolite concentrations. The PES-Ce0.6 membrane achieved a water flux of 86 L/m2h at 5 bar, significantly higher than the unmodified PES membrane's 39 L/m2.h. Antifouling tests revealed a 92% flux recovery ratio (FRR) for PES-Ce0.6. Pharmaceutical rejection tests showed up to 97% removal of various pharmaceuticals, including approximately 94% removal of amoxicillin (100 ppm), and high removal rates for penicillin G, levofloxacin, famotidine, ranitidine, and cefamezin. Life cycle assessment (LCA) demonstrated significant environmental benefits for the modified membranes, including reductions in human health damage (up to 48.95%), ecosystem damage (up to 23.97%), and resource depletion (up to 47.66%), with a 34.46% total weight improvement for the PES-Ce0.6 variant. These results indicate that Ce-NaY zeolite modification enhances PES membranes' performance and sustainability for water purification and pharmaceutical removal.
